Sun information for kids

Information about the Sun's formation, composition, statistics, and eventual demise suitable for young astronomers.

Photo Credit: Duncan Walker

By Melissa Mayntz
The Sun is the largest, most familiar object in the solar system, and without it, no life could exist on Earth. The Greeks and Romans worshiped the Sun because of its importance. The Sun provides most of Earth's energy through heat and light, and scientists have studied it for decades to discover how it works.

The Sun was born nearly five billion years ago from a cloud of gas and dust called a nebula. The gas and dust swirled around until it condensed into a tremendous ball of gas which became our Sun. Leftover gas, dust, and rocks became the nine planets and over one hundred moons that make up the solar system. Everything in the solar system orbits the Sun, and the Sun orbits the center of our galaxy, the Milky Way. The Milky Way is much bigger than the solar system: the Earth orbits the Sun once a year, but the Sun takes over 200 million years to orbit the galaxy!

The Sun is seventy-five percent hydrogen and twenty-five percent helium. Tremendous pressure fuses hydrogen atoms together in the Sun's core to make helium. This fusion is the same process that happens in powerful hydrogen bombs. The Sun fuses together millions of tons of hydrogen every second, and that energy makes the core's temperature about 28 million degrees Fahrenheit (16 million degrees Celsius). The Sun is so hot that the surface bubbles and looks like grains of sand that scientists study to learn about how the gases move.

Just like the Earth is made up of different layers, the Sun has layers too. The innermost layer after the core is the radiation zone, where most of the energy is light. It is so crowded and dense that light can take thousands of years to get out of the radiation zone. Next is the convection zone, where the energy is mostly heat. The Sun's surface is called the photosphere. Just like Earth, the Sun has an atmosphere, but it isn't made up of air. The Sun's atmosphere has two layers, the chromosphere and the corona, and they are the areas where energy is streaming out into the solar system on its way to Earth. The corona is the outermost layer and is about 4 million degrees Fahrenheit (2.2 million degrees Celsius); it is actually hotter than the chromosphere.

The Sun's surface is not smooth and uniform. Just like Earth has mountains, valleys, and oceans, the Sun has sunspots and storms. Sunspots are cooler areas on the Sun's surface, and they look like dark freckles through a telescope. Every eleven years there are more sunspots than normal, but scientists haven't discovered why. Solar storms are huge flares, like giant flames, that spurt out of the Sun's surface. They can be spikes, waves, or huge arches thousands of miles long. These storms are caused by the Sun's magnetic field, and scientists are always studying new storms to learn more about how the Sun works.

The Sun also gives off solar wind. You can't feel it, but you can see it. Solar wind is part of the corona, the outer layer of the Sun's atmosphere, streaming off into space. The particles move very fast - over 150 miles per second - and when they run into the Earth's atmosphere, they make the aurora, also called the northern or southern lights. These bright green, blue, and red lights are from the particles' interaction with Earth's magnetic field.

The Sun doesn't seem so hot or large because it is very far away - over 93 million miles from the Earth. The sun is only a medium size star, but it is still 864,000 miles (1.4 million kilometers) in diameter. That's bigger than one million Earths! Light travels very fast - 186,200 miles per second - but it still takes over eight minutes to get from the Sun to the Earth. The Sun also has gravity but it is more than twenty-eight times as strong as Earth's gravity - if you were on the Sun, you would weigh twenty-eight times mores than you do on Earth.

All stars are like the Sun, and many are even bigger and more powerful. Other stars look like tiny points of light because they are so far away. The next-nearest star is Proxima Centauri, and it is more than 265,000 times further away than the Sun!

Because the Sun is so hot and bright, it is very hard to study. During an eclipse, when the Moon blocks most of the Sun from our view, scientists can learn a lot about the corona and solar storms. Satellites help gather information about the Sun because they are above the Earth's atmosphere and can study all the different radiation the Sun sends out. A lot of that radiation never reaches us because our atmosphere absorbs it. From studying similar stars, scientists believe that the Sun will live another five billion years, and then it will gradually get weaker as all the hydrogen is used up. Eventually, it will use up all its fuel and become a white dwarf star, which is just the core of the Sun. Today, scientists use solar energy to run cars, televisions, air conditioners, and other electrical appliances: solar energy is free, clean, and there is plenty to go around.

The Sun is our most familiar star. Like all stars, it gives off heat and light, but it seems very different because it is so close. Without the Sun, the Earth would be frozen and dark and no life could exist here. Every sunrise starts a new warm, bright day - all thanks to the Sun!